In the well known I.S. (individual section) machine for the manufacture of glass containers, molten glass is formed into containers in moulds, a parison being formed in a blank mould, the parison being transferred to a blow mould and, in the blow mould, blown into the required shape.
It is necessary to cool the moulds to maintain them at the appropriate temperature for these forming operations. While in recent years the cooling of the moulds by the flow of air through axial holes in the moulds has become increasingly popular, extensive use is still made of what is known as `stack cooling` in which cooling stacks are arranged close to the moulds of the machine and cooling air is supplied to the stacks and is directed through openings in the stack against the mould to cool it. Normally this air is directed against the moulds when the moulds are open. A valve is provided to give on-off control of the air.
Stack cooling is shown for example, in U.S. Pat. No. 3,355,277. As is usual in stack cooling systems this specification shows an on-off valve which is a flap valve. Because of the continuous wear on these valves they need fairly frequent replacement, and because of their construction they are comparatively expensive.
It is one of the objects of the present invention to provide a valve for use in an air line of a cooling system of a glass container manufacturing machine which is both economical and efficient in construction.